.app{
    display: flex;
    flex-flow:column;
    height:100vh;
}
.app > ul{
    display: flex;
    flex-flow: row;
    align-self: flex-end;
    width: 100%;
    margin:0px;
    padding:0px;
}
.app > ul> li{
    flex:1;
    text-align: center;
    height:80px;
    background-color: #17A396;
    color:#fff
}
.app > ul> li:hover{
    background-color: #00a38c
}
a{
    text-decoration: none;
    height:80px;
    line-height: 80px;
}
body{
    margin:0px;
}
ul{
    margin:0px;
    padding:0px;
}
ul li{
    list-style: none;
}